No it is not perfect. None are constrained.
Since you should constrain all geometry in a sketch, you have gained little by snapping to the grid.
Using the ctrl key restricts the arcs to 90 degrees. So, if your first edge is added with a horizontal or vertical, then using ctrl key make an arc 90 degrees and the next line is going to be orthogonal to the first.
In addition, drawing a rectangle of this shape is far faster using the rounded rectangle tool.
In the end you should use what you feel comfortable with.